A novel hamster separation model of depression is under development for analysis of central neurochemical changes during a behavior state of separation which may be analogous to human depression. Separated male dwarf hamsters show increased body weight, decreased exploratory behaviors, and reduced social interactions. High pressure liquid chromatography assays of brain monoamines and metabolites failed to detect significant differences in separated hamsters as compared to hamsters remaining in male-female pairs. Autoradiographic assays of opiate receptors failed to detect significant differences between separated and paired hamsters on 3H-naloxone binding.